Question: If $a + b + c = -7$ and $x + y + z = 8$, what is $3b - 6x + 3a + 3c - 6z - 6y$ ?
Explanation: $= 3a + 3b + 3c - 6x - 6y - 6z$ $= (3) \cdot (a + b + c) + (-6) \cdot (x + y + z)$ $= (3) \cdot (-7) + (-6) \cdot (8)$ $= -21 - 48$ $= -69$